Most ballistic security barriers you work on will rely on bulletproof acrylic glass, either on its own, or as part of a laminated window product. Acrylic bulletproof glass stops shots from most common caliber pistols, making it a popular option for many organizations and businesses. Knowing a few facts in advance will help ensure that even your first experience working with bulletproof acrylic sheets is a good one.
The Two Main Types of Ballistic Acrylic Glass
Bulletproof acrylic glass usually falls into two categories—monolithic acrylic and an acrylic core laminated between two thin sheets of polycarbonate.
Monolithic Acrylic Ballistic Glass
Monolithic acrylic is just what it sounds like: a solid slab of clear acrylic, usually between 1 ¼ inch and 1 ⅜ inch thick. Acrylic has excellent optical clarity at 90% visible light transmission (VLT). Acrylic is also relatively easy to work in the field. It’s most suitable for UL Levels 1 and 2 security. Acrylic also poses a minor risk of injury when shot, because acrylic produces spall when it stops a bullet.
Laminated Polycarbonate/Acrylic Glazing
Laminate polycarbonate/acrylic bulletproof glazing (also referred to as LP1250) has a 1-inch acrylic core with ⅛-inch polycarbonate end caps on each side. This configuration combines the strongest aspects of both materials; the acrylic provides a high level of optical clarity and is easy to work with. Laminated polycarbonate/acrylic doesn’t spall and offers increased resistance to forced entry and blast impact. As a result, laminate polycarbonate/acrylic can stop common pistol calibers at UL Levels 1, 2, and 3 while remaining a slim profile. Laminated polycarbonate/acrylic’s VLT is closer to 80 percent, creating the appearance of being slightly tinted.
Three Tips for Success with Bulletproof Acrylic Sheets
Total Security Solutions CEO Jim Richards finds that, with proper care and attention to detail, most glazers and contractors can have a good experience installing bulletproof acrylic glass. Save yourself on-site headaches and hassles with these three tips.
#1: Be Careful! Bulletproof Doesn’t Mean Indestructible
“For people handling acrylic glazing for the first time,” Jim explains, “I think the biggest misconception is thinking that because it’ll stop a bullet, it’s indestructible. That is not remotely the case.”
Both acrylic and polycarbonate are thermoplastics. They don’t stop bullets because they’re stronger or harder, but because of their unique plastic qualities.
“Acrylic and polycarbonate both scratch fairly easily if you’re not paying attention,” Jim says. “Hit it with a tool, let a drill bit walk across it when it slips out of a screw and you'll leave a mark.”
Treat bulletproof acrylic glass as you would any other window: Don’t drag it, drop it, step on it, or set it down on its corner or the window will blow out from the weight.
You also want to be very careful how you clean all types of bulletproof acrylic glazing. Taking a razor to the surface is definitely a bad idea, but also look out for common glass cleaners like Windex or Clorox. These usually contain chemicals that will cause crazing and hazing in thermoplastics. Crazing and hazing won’t compromise the glazing’s ballistic qualities, but it will cause permanent cosmetic damage. Instead, clean your ballistic acrylic products with a gentle soap and water, or a specialized bulletproof glass cleaner.
#2: Acrylic Sheets Are Hard—and That’s a Good Thing
While not indestructible, acrylic glazing is quite hard—which actually makes it easier to work in the field.
“With monolithic acrylic, you can do a lot in the field if you have the right tools,” Jim notes. “You can notch it, drill it, cut it with a circular saw. It actually cuts halfway decently, because it’s a hard, rigid material. But you need the right tools. Don’t just use any old blade. Get a good horsepower saw and a sturdy blade. Be careful of deflection when you cut, and remember that the blade will heat up, and you’re dealing with plastic.”
If you suspect you’ll need to modify acrylic in the field, TSS recommends keeping a dedicated saw blade you only use on acrylic. To cut the thickness used in ballistic systems, that should be a 12-inch to 14-inch 60-tooth carbide blade with triple-chip teeth. Choose one that’s tempered to 42 to 46 HRC, which will minimize deflection.
After cutting, the edge of the acrylic can be sanded, buffed, and polished—or even flame-polished—in the field.
“You have to be careful with acrylic,” Jim concludes. “That rigidity and hardness means it’s prone to chip—if you drill through with the wrong acrylic bit or aren’t careful, it can blow the back side out pretty easily.”
#3: Acrylic/Polycarbonate Glazing Can Be Worked in the Field, to a Limited Degree
Despite the difference in strength and makeup, you can also drill, cut, notch, sand, buff, and polish polycarbonate/acrylic glazing on-site.
“It’s definitely possible,” Jim says, “because it’s fundamentally the same thing: it’s an acrylic core. You only have ⅛ inch of polycarbonate on each side.”
But that ⅛ inch of polycarbonate does make things tricky. You’ll still want high-horsepower tools with dedicated harder blades and bits. You may even notice that the polycarbonate caps tend to get ‘gummy’ as you drill or cut. Fortunately, this also reduces the risk of a bit walking across the surface or the bulletproof acrylic core blowing out.
“You can still cut it. You can still notch it. You can still route it. But when you’re done, if you’re not extremely familiar with it, you would just want to buff it instead of trying to flame polish it on-site. If you get the polycarbonate too hot, it gets all bubbly and gooey, because it melts at a lower temperature than acrylic. That’s no good.”
In house, TSS uses a special chemical treatment to finish the edges of bulletproof glass made with polycarbonate and acrylic, giving them an unparalleled lucid shine. But this process uses harsher chemicals and shouldn't be attempted on a job site.
Learn More About TSS Bulletproof Acrylic Glass Solutions